Abstract: The synergistic effects of the mixtures of Dimethomorph with Chlorothalonil were tested against Phytophthora capsici Leonian at different stage,in vitro. The results showed that the mixtures of Dimethomorph with Chlorothalonil at the ratio of 1 to 11,in the 11 mixed preparations,was synergistic in inhibiting the formation of sporangium,the germination of zoospores and mycelium growth,and the synergistic ratios (SR) of the mixtures of the two compounds were respectively 1. 54,2. 37 and 1. 86. The SR of the mixtures at the ratio of 1 to 9,in inhibiting the germination of zoospores,and 11 to 1,in inhibiting the mycelium growth,were respectively 1. 59 and 1. 50. At the same time,the Protective efficacy and the duration of efficacy of Mixtures of Dimethomorph and Chlorothalonil were tested respectively at the best ratios of 1 to 11 and 11 to 1. The Protective efficacy of the mixtures at the ratio of 11 to 1,with the concentrations of 10,5 and 1 mg /L,was obviously stronger than the independent's at the same concentrations. The relative control effect at the concentrations 10 mg /L was still as high as 67. 50% after 14 days.There was also a significant difference between the mixtures at the ratio of 1 to 11 and Dimethomorph with a higher protective efficacy and a longer duration of effectiveness for 2 to 3 days at the concentrations 10 mg /L. Compared with the same concentration of Chlorothalonil,the preventive efficacy was also relatively higher.

Key words: Dimethomorph, Chlorothalonil, Phytophthora capsici, Synergism, Protective efficacy

CLC Number: 

• S482.2